1. Field of the Invention
The present invention relates to an anti-fogging glass, which is designed to prevent fogging by heating the glass plate by supplying power to a heating unit formed on the surface of the glass plate.
2. Discussion of Background
As a window glass to be mounted in e.g. a rear window frame of an automobile, an anti-fogging glass having an anti-fogging function is commonly employed to secure safe visibility. Such anti-fogging glass is provided on the surface thereof with a heating unit formed by printing a conductive paste such as silver in a suitable pattern on the surface of a glass plate, followed by heating and baking it.
A conventional structure of an anti-fogging glass for an automobile, provided with a heating unit, is shown in FIG. 8. The heating unit comprises a plurality of lines, and has heating lines (heat strips) 71 having a narrow width (from about 0.5 to 1 mm), formed to extend substantially in parallel with one another with a distance of a few tens mm in a longitudinal (transverse) direction of the anti-fogging glass and a pair of symmetric bus bars 73 having a large width formed in the vicinities of the short side edges of the anti-fogging glass in the short side direction (vertical direction) of the anti-fogging glass, to which both ends of these heating lines 71 are connected. Further, at the lower end of each bus bar 73, a terminal 75 for connecting a power supply wire (not shown) connected to a power source of an automobile, to the bus bar 73, is provided and fixed by e.g. solder.
When power supply to the heating lines 71 is carried out with such a conventional anti-fogging glass having the above described construction, a current obtained from the power source of an automobile is supplied to the bus bars 73 via the power supply wires and the terminals 75 and from the bus bars 73 to the respective heating lines 71. The heating lines 71 are thereby heated, so that the glass plate 77 is heated mainly in the anti-fogging region 79.
As described above, the anti-fogging glass is designed to remove or prevent deposition of e.g. moisture, frost or icing on the surface of a glass plate by utilizing heat generated by the heating lines 71, thereby to secure the transparency of the glass.